Mixing process



April 2, 196s J. R. LAGE r MIXING PROCESS Filed Aug. 17, 1965 6 /6 u 5 FgJ.

i In? -7-2 Y United States Patent O 3,376,023 MIXING PROCESS James Richard Lage, Krchhalde 186, Umiken, Brugg, Switzerland Filed Aug. 17, 1965, Ser. No. 480,301 Claims priority, application Switzerland, Aug. 28, 1964, 11,314/64; Jan. 28, 1965, 1,203/ 65 4 Claims. (Cl. 259-4) ABSTRACT OF THE DISCLOSURE The apparatus includes a hollow, cylindrical casing with a mixing chamber therein, an outlet and a centrally apertured end wall. Also an elongated insert body is supported coaxially in the chamber and a cylindrical outlet conduit is -connected coaxially to the end wall. The method comprises mixing of materials in certain flow paths of which there are four in number, each path comprising a portion of the material.

This invention relates to the mixing of s-ubstances. The term mixing is used in a broad sense and includes agitation or stirring. The mixing may be direct for example for homogenising, production of mixtures, flotation, production of dispersions, suspensions, colloidal solutions and emulsions, or indirect for example for influencing, in particular accelerating dissolving operations chemical, physical or atomic reactions, fermentations, the gasifica- `tion of liquids, the washing Iof gases in liquids or of liquids by gases, and the fine grinding of granular or pulverulent substances by mutual abrasion of the particles. The mixture may have liquid, pasty, gaseous, granular or pulverulent ingredients.

An object of the invention is to eifect mixing rapidly and intensively in a simple manner and with simple means involving low power consumption.

The method according to the invention comprises leading material containing at least one ingredient of the mixture out of a chamber under pressure in the `form of a current which is at rst annular in form, thereafter directing it towards the axis of the annular cross section and nally leading it out coaxially with this axis.

Apparatus according to the invention includes a chamber en-closed Iby a casing and held under pressure, to which the material containing at least one component of the mixture is supplied an annular passage leading from the chamber preferably bounded by two coaxial surfaces of revolution, and a coaxial outlet following the passage in the direction of flow, the diameter of which is smaller than the internal diameter of the annular passage.

The technical advantage of the method and of the action of 'the apparatus is in essence that the material, after it has been accelerated in the annular passage, flows from all sides towards the axis of the annular passage, where the particles of the material impinge against one another. The term particles is used in a broad sense to in` dicate small portions, not necessarily discrete. At the same time while the particles are thus impinging against one another the material is -under a substantial damming or static pressure because the cross section for the flow directed from all sides towards 'the axis is 'diminishing and the discharge after the mutual impingement takes place in the direction of the axis, that is after being changed in direction. Accordingly what can be termed a grinding action occurs during this already highly effective mutual impingement. That this action occurs is obvious in the case in which granular pulverulent material is mixed with a gas for the purpose -of very tine grinding. But the 3,376,023 Patented Apr. 2, 1968 mixing of liquid or pasty and/or gaseous substances will be greatly intensified and accelerated =by similar action.

The parts essential for description of examples of apparatus embodying the invention are diagrammatically illustrated in the accompanying drawings. In conjunction with the apparatus, examples of the method of the invention will 'be described. The same parts are given the same references in the different views all of which are axial sections.

FIGURES 1 and 2 show the two different examples of mixing apparatus,

FIGURE 3 shows a combination of the devices of FIGURES l and 2,

FIGURE 4 shows a further `development based on FIG- UR-E 2, for a particular use.

The apparatus of FIGURE 1 comprises an essentially lcylindrical casing 1. In the part which is uppermost in the figure, a cylindrical chamber 2 is formed, the top of the casing and its closure not being shown. This chamber is closed apart from a passage tobe described. The upper end surface 3 of a cylindrical insert 4 coaxial with the chamber 2 forms the bottom of the chamber 2. Below the insert 4 the casing has an inward step S which leaves an outlet 6 coaxial with the chamber 2, the diameter of which is smaller than that of the insert 4. The cylindrical surface 7 of the insert 4 and the opposite part 8 of the internal wall of the casing form between them an annular passage 9 leading from the chamber 2 and opening into a further passage 10 which is formed between the lower end surface 11 of the insert 4 and the annular sur- Iface of the shoulder 5, and leads to the outlet 6.

The components of the mixture are fed into the charnber 2 which is under pressure, either individually or more or less premixed, as indicated by the arrows 15, under the action of the pressure, the material flows at accelerated speed through the annular passage 9, and then, its speed becoming ever greater, from all sides towards the geometric axis of the casing, that is radially inwardly. There the particles of the material impinge against one another while they are under a considerable damming or static pressure because the flow cross section in the passage 10 decreases towards the .axis and the radially inwardly directed flow is finally turned through a right angle, in the drawing downwardly. During the mutual impinge- Irnent `the ,particles of the material under pressure are intensively mixed and it leaves the casing 1 through the outlet 6 in the direction of the arrow 16. Further arrows not referenced indicate the above described tlow in the caslng.

FIGURE 2 shows another form of apparatus. The casing 1 contains coaxially with the chamber 2, an insert 12 which is not cylindrical, but has the form of a body of revolution widening streamline fashion from the top downwards in the drawing. At the tail end it is bounded by a surface normal to the axis. Between the curved upper surface 7 of this insert and the internal wall 8 of the casing 1, an annular flow passage 13 is formed, which in the direction of ilow is of smoothly decreasing cross section which facilitates the ow of the material.

The insert in the mixing apparatus of the invention is not necessarily bounded by a surface normal to the axis, nor it is necessarily located directly above the outlet, but can, as FIGURE 2 shows be at some distance and their dissipation into ever finer eddes, and the material is mixed by this action. By the reduction of the cross section of the outlet 14 which follows the passage 13 and chamber 2 in the ow direction, the ow is again accelerated and is given a component of flow directed towards the geometric axis of the casing 1 so that inthis example again the particles of the material which have already been premixed to a considerable extent, strike one another and the mixing is thus supplemented.

The inserts 4 and 12 are supported in the casing 1 by bars or webs not shown. These bars or webs are so formed and located that they hinder the iiow of material as little as possible. Each of the inserts 4 and 12 may be axially adjustable to vary the mixing action and may be exchangeable for other inserts, for example of different diameter.

To achieve a very high degree of homogeneity of the mixed material and with components which are particularly difficult to mix two or more mixing devices may be arranged in series. Here similarly or dierently constructed devices can be combined. It simplifies the construction of such combined devices if the diameter of the casing of the device which in the flow direction comes second, is of the same diameter as the outlet from the first. By the use of a multi-stage mixing process, the time the material is in the apparatus is prolonged and the mixing is correspondingly improved.

A combined apparatus is shown in FIGURE 3, in which the material first ilows through a device as in FIGURE 1 and then through a device as in FIGURE 2. The second insert 12 is mounted in the extended outlet 6 of the rst device which acts as the chamber 2 of FIGURE 2 for the second device. It is desirable for the distance of the insert 12 from the first insert 4 and from the outlet 14 to be at least equal to the diameter of the outlet 6 because by the incorporation of a stilling length following the striking together of the particles Iafter the insert 4 and the utilisation of the possibility of eddying after the insert 12 the greatest mixing action is obtained.

If at least one further component of the mixture must be rapidly admixed with the rest of the material, as for example may be necessary to avoid spontaneous combustion, the above described mixing apparatus can be used with very simple supplementary means. FIGURE 4 illustrates an example. As in FIGURE 2 an insert 12 is disposed in the casing 1, on the inside 8 of which, in the illustrated example in the region of the outlet end of the ,annular passage 13, a peripheral groove 21 is provided into which a supply pipe 17 open-s. A further supply pipe 19 leads through the insert 12 and opens at 20 into the tail end.

Material containing at least one component of the mixture is supplied to the chamber 2. At least one further component of the mixture which is to be rapidly admixed with the aforesaid material is supplied through the pipe 17 or the pipe 19 or through both. A component supplied through the pipe 17 reaches that zone in the ow of the material at which it has left the smallest cross section of the annular passage 13 and is therefore at its highest speed. This component will therefore be very rapidly carried along by the material and distributed therein. Thereafter intensive mixing takes place when the material flows inwards towards the axis of the device. A component supplied through the pipe 19 reaches the flowing material at the zone where the particles impinge against one another and is there also rapidly and intensively mixed with the material.

The device of FIGURE4 can naturally be constructed without the pipe 17 and groove 2l or without the pipe 19. Also either or both of `these arrangements for the admixture of an additional component or components could be used in a device according to FIGURE 1, or in either or both of the stages of the apparatus of FIGURE 3.

Although the devices are shown in the drawing disposed in the vertical position which in itself is desirable, they can .be used in inclined or horizontal position, especially with components of equal specific gravity or when operated with high ow speeds.

I claim:

1. A method of mixing which comprises causing material containing at least one ingredient of a required mixture to ow under pressure along a path successively including a rst flow path portion of non-turbulent tubular form, a second flow path portion of annular form having non-divergent radial dimensions therealong in the direction of iiow and being 0f lesser cross-sectional area than that of said iirst ow path portion to effect accelerated non-turbulent flow of said material, a third low path portion of disc form disposed coaxially with said second ow path portion to eiect iow of said material radially inwardly to impinge centrally thereof in a grinding action under damming pressure, and a fourth non-turbulent ow path portion of cylindrical form coaxial with and having a diameter less than the internal diameter of the downstream end of said second ow path portion.

2. A method according to claim 1 wherein said second ow path portion is defined by coaxial cylindrical surfaces, and the radially outer limi-ting surface of both said iirst and second ow path portions being formed as that of a common cylinder.

3. A method according to claim 1 which comprises leading another ingredient of said mixture into the flow path by injection axially of Said second ow path portion into said third flow path portion.

4. A method according to claim 1 which comprises leading another ingredient of said mixture by injection radially into said `third ow path portion.

References Cited UNITED STATES PATENTS 562,089 6/1896 Oakman et al. 239-432 X 1,089,033 3/1914 Arthur 239-432 3,207,492 9/1965 Zikesch 239--434 X 3,239,960 3/1966 Stevens 239-432 X 1,093,385 4/1914 Clemmer 13S-42 X 1,097,474 5/1914 Scheoder 138-40 X 1,124,579 1/1915 Ambursen 259--151 1,534,008 4/1925 Bongardt 259-151 X 1,884,423 10/1932 Walker 259-151 X 2,048,613 7/1936 McKee 13S-40 X 2,662,590 12/1953 Reich 13S-42 X 2,726,841 12/1955 Crist 138-42 X WALTER A. SCHEEL, Primary Examiner.

J. M. BELL, Assistant Examinez'. 

